Power Brake Boosters and Turbos

[Dave A.]

Just curious......but how many peeps that have done turbo conversions on their MKII's have installed a check valve in the vacuum line to the power brake booster to prevent boost pressure from damaging the diaphragm?

[Ross]

Use the one off the 7M-GTE donor car

[Junkie]

Have run with and without.But,I'm with Ross.Haven't lost a booster yet,but have never ran a high boost car without the valve either :wink:

[MkIISuperSupra]

I have a check valve in front of my booster.

Leslie

[Suprajayaz]

I have one also.. Thanks Shawn/Don. I did not have one for the heater valve and when driving up north (from 1200 ft above sea level to ~ 6k ft), I'd loose vacuum to the heater valve.. Long hills = extended boost periods = no vacuum = no heat..I have a 1 way valve in there now, but till loose vacuum to the heater valve.. Not a major ordeal, but think that a larger vacuum canister may be needed for those living in cooler climates.. Jay B

[MkIISuperSupra]

Jay, you are absolutely right. Wasn't even thinking about the check valve in front of the vac cannister. I ended up putting one in there as well. Same reason..... can't leave town without climbing mountains and yeah....extended periods of boost as I pass everyone on the road going up steep grades. 8-)

Leslie

[Funkycheeze]

that vac canister works as a check valve, but a larger one like is on the mk3T would be a good upgrade

[Dave A.]

that vac canister works as a check valve


:? Is the vacuum canister controlled by a VSV that disconnects the canister from intake manifold vacuum after vacuum drops below a specified amount? If not, then there's no way the canister can act as a check valve. More like a small storage tank that would store air under pressure when the turbo starts to build boost pressure.

[Obocecha]

I've been running my 6M-GTE for a few years now with no check valve for the brake booster. Haven't had a single problem yet with it.

[Funkycheeze]

that vac canister works as a check valve


:? Is the vacuum canister controlled by a VSV that disconnects the canister from intake manifold vacuum after vacuum drops below a specified amount? If not, then there's no way the canister can act as a check valve. More like a small storage tank that would store air under pressure when the turbo starts to build boost pressure.

it has a little diaphragm in it that prevents air from entering it - the engine can only 'suck' air out - thus when the manifold pressure exceeds that in the vac canister, air will not flow into the canister

[williamb82]

i have the check valve on mine. never tried it without. figure its not worth the chance of messing up the booster.

[Dave A.]

that vac canister works as a check valve


:? Is the vacuum canister controlled by a VSV that disconnects the canister from intake manifold vacuum after vacuum drops below a specified amount? If not, then there's no way the canister can act as a check valve. More like a small storage tank that would store air under pressure when the turbo starts to build boost pressure.

it has a little diaphragm in it that prevents air from entering it - the engine can only 'suck' air out - thus when the manifold pressure exceeds that in the vac canister, air will not flow into the canister


Interesting! Thanks for that info.! The MKIII turbo also has a small electric vacuum pump.

A friend of mine has a turbo DSM car :roll: that has quite a few miles on it, and the diaphragm in the booster gave out when the boost hit 10 psi.. And...silly me forgot to install a check valve in the vacuum line to the booster. Ahh well, the car deserves to have it's booster blown to bits considering all of the grief that it's caused me over the past 2 +years. :wink: Now to find a replacement booster! Tons of DSM cars in the junk....but naturally...... the booster for the 2.0L turbo GS is specific to the turbo GS only, just like the half a million other parts that I had to scrounge from all over Florida. :mad: